The present invention generally relates to a battery pack, and more particularly relates to a battery pack for containing electrochemical cells.
Battery packs containing electrochemical cells are in widespread use with a wide variety of portable electronic devices. Packs are utilized for a variety of reasons, including but not limited to, the ease and efficiency of providing a series or a parallel connection for the cells as part of the pack, depending on the voltage provided by each cell and the power requirements of the device, thereby obviating the need for the device to provide the appropriate cell-to-cell contacts for accepting individual cells.
Battery packs are typically made by joining one or more component pieces together. Such pack components can include cell receiving sections, one or more end caps and one or more terminals for making electrical connection between the cells and the device. The components may be welded together, adhesively joined together or snap fit together at some point in the manufacturing process. Additionally, some packs may include an external adhesive label that provides a surface for conveying desired information concerning the pack and can also serve to hold the cells and the various structural pack components together in a single cohesive unit. Such packs are disclosed, for example, in U.S. Pat. No. 5,744,260, U.S. Pat. No. 4,965,148 and U.S. Pat. No. 6,218,042.
These packs present certain disadvantages. The required joining together of the structural pack components increases the potential for disassembly of the pack during labeling and other handling. Further, the number of structural pack components complicates the manufacturing and assembly processes.
There is therefor a need for a pack that minimizes the number of component parts while maintaining sufficient structural integrity to protect the appropriate cell-to-cell contacts within the pack and provide a cohesive unit.
Accordingly, it is an aspect of the present invention to provide a battery pack comprising a battery pack frame. The battery pack frame is a single integral part. The frame comprises first and second endcap portions and first and second spine portions. One of the spine portions has a free end, allowing the spine to be flexed so as to provide an opening. The opening provided by the flexing of the spine preferably enables a cell assembly to be inserted into the frame, where a cell assembly comprises at least two cells and a cell-to-cell connection that provides either a series or a parallel connection between the cells. The flexing spine preferably has a length of at least fifty percent of the total length of the frame, thereby providing added support to the frame while still allowing for insertion of a cell assembly into the frame.
The pack enables the use of the external cell contacts to provide an electrical connection directly to the device contacts, obviating the need for the pack to include discrete external terminals. In one embodiment of the battery pack of the within invention, the pack comprises two 1.5 volt standard sized AA cylindrical cells employing a lithium nonaqeuous cell chemistry. In this embodiment, the cells are connected in series by a simple nickel tab to create a 3.0 volt cell assembly. The untabbed positive terminal of one cell and the untabbed negative terminal of the second cell are accessible through one or more openings in an endcap portion and make electrical contact directly with the device terminals, thereby avoiding the complex additional tabbing required where 3.0 volt cells are connected in parallel.
These and other features, advantages, and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings.